1. Technical Field
The present disclosure relates to an optical measuring system and an optical measuring device thereof, specifically, an optical measuring system and an optical measuring device with light collecting lens modules.
2. Related Art
At each stage of the light emitting diode (LED) production, the use of measuring devices to measure the properties of the LED in electricity, radiometry, photometry and colorimetry is required. The method of measuring the LED luminous flux, for example, is to place the LED inside an integrating sphere, which is connected to a photodetector. Once the power is on and lights up the LED, the light emitted from the LED scatters uniformly all over the inner surface of the integrating sphere and the illuminance on the inner surface of the integrating sphere is detected by the photodetector in order to measure the total luminous flux of the LED.
When the LED production is still at its wafer stage prior to cutting the LEDs apart, a pair of test needles is used to transmit electricity to the electrodes of the LED chip as a means to light it up. However, due to the size of the LED wafer, the measuring process is conducted with the LED sitting outside the integrating sphere instead of within thereof. The light emitted by the LED, which resides outside the integrating sphere, enters the integrating sphere through an opening on the integrating sphere and a photodetector then intercepts the light, which has been uniformly scattered inside the integrating sphere, for calculation.
Due to the spatial distribution of the light emitted from LED, the further distance between the integrating sphere and the LED is, the opening on the integrating sphere needs to be bigger for flux measurement, and the bigger the integrating sphere is needed therefore. According to the design principle, the area of the opening on the integrating sphere shall be less than 5% of the inner surface of the integrating sphere. Therefore, the diameter of the integrating sphere currently adopted by industry for measuring the luminous flux of the LED at its wafer stage reaches 2 inches or larger.
There are several LED dices on one wafer when the LEDs production is at its wafer stage. Being able to measure multiple LEDs on the same wafer simultaneously can increase the measuring efficiency dramatically. However, the size of the integrating sphere is comparably large, thus making it impossible to place multiple integrating spheres above a wafer to measure several LEDs simultaneously. As a result, the efficiency of inspecting the optical properties of LEDs during wafer level is difficult to improve.